My iphone 4 just developed a problem a couple days ago where the 3G will just drop and stop working. Wi-fi works but anything dependent on 3G doesn't, ie text messaging. If I do a hard reset, 3G will work immediately after but stops working again after a minute or so of use. I've done a restore and updated to 4.1 but the problem still exists. I find it weird that the problem just suddenly started (I've had the phone since launch). Any ideas?